Hydrodynamic transmission



Jan. 26, 1954 P. c. ACKERMAN 2,667,085

' HYDRODYNAMIC TRANSMISSION Filed March 18, 1950 3 Sheets-Sheet l #fron/V504?.

P. c. AcKr-:RMAN 2,667,685 HYDRODYNAMIC TRANSMISSION Jan. 26, 1954 3 Sheets-Sheet 2 Filed March 18, 1950 Jan 26, 1954 P. c. ACKERMAN HYDRODYNAMIC TRANSMISSION 3 Sheets-Sheet 3 Filed March 18, 1950 IN V EN TUR. Paz/f6'. /7cierfffd7z e va NL Patented Jan. 26, 1954 HYDRODYNAMIC TRANSMISSION Paul C. Ackerman, Detroit, Mich., assignor to Chrysler Corporation, Highland Park, Mich., a

corporation of Delaware Application March 1s, 195o, serial No. l150,490

(ci. 74c45) 24 Claims. l

This invention relates to a hydrodynamic power transmission unit comprising a hydrokinetic torque converter and a planetary gear box arranged in series and adapted to be drivingly connected in a plurality of different ways such that a plurality of different torque multiplying, starting, drive ratios are obtainable, each of which is adapted to be automatically converted into a positively connected direct drive for cruising purposes.

It is a primary object of this invention to provide a simplified, highly flexible, form of hydrodynamic power transmission unit having a plurality of different torque multiplying, starting, drive ratios, the transmission including suitable control means whereby each or" the starting drive ratios is automatically convertible into a positively connected, ecient, direct drive ratio.

It is a further object of this invention to include in this transmission unit control means to automatically effect the upshifts and downshifts between each of the torque multiplying, starting, drive ratios and, in addition, manually or driver operable means to overrule the automatic control means whereby a downshift from the positively connected direct drive to the selected starting drive may be effected at the will of the operator.

It is another object of this invention to provide control means for a transmission of this type whereby the power transmission unit may be locked in a positively connected, torque multiplying, underdrive ratio so as to provide a drive ratio particularly adapted for coast braking purposes.

Other objects and advantages of this invention will become readily apparent from a reading of the attached specification and a consideration of the related drawings wherein:

Fig. 1 is a sectional elevation of a torque converter driven planetary gear type power transmission unit embodying this invention;

Fig. 1A is a sectional elevational view taken along the line IA-IA of Fig. 1 disclosing the oneway brake structure associated with the converter guide wheels;

Fig. 2 is a diagrammatic view of part of the control system for this power transmission unit with certain portions thereof shown in sectional elevation; and

Fig. 3 is a diagrammatic view of the complete control system for this transmission with certain portions thereof shown in sectional elevation.

Fig. 1 of the drawings discloses a power transmission unit comprising a hydrokinetic torque converter unit A arranged in series with and operatively connected to a planetary gear box B. Converter unit A is adapted to drivingly connect a prime mover such as a motor vehicle engine to the input to the planetary gear type torque transmitting and torque multiplying unit B. The reference numeral 8 represents an end portion of a driving member, such as the engine crankshaft of a motor vehicle power unit. The shaft 8 is drivingly connected to the rotatable, somewhat axially flexible, drive transmitting plate 9 by the screw means I0. The drive transmitting plate 9 has an engine starter ring gear I I xedly mounted about its periphery. Also drivingly connected to the drive plate 9 by the bolt means I2 is the torque converter casing I3 within which are mounted the various converter components, namely, the pump or impeller member I4, the turbine or runner member I5, and the guide wheels or reaction members il and I8.

The vaned impeller wheel Id is iixedly connected to the converter casing I3 by welds, rivets or the like and is accordingly adapted to be rotatably driven by the driving shaft 8. The vaned turbine wheel I5 is mounted on and drivingly connected by rivet means I9 to a radially extending ange portion ISb formed on the shaft hub member Ita. Hub member Ilia is drivingly connected to the forward end portion of the intermediate driven shaft member I6.

The intermediate shaft member I6 is adapted to transmit drive from the turbine member I5 of the torque converter unit A to the planetary gear unit B. Shaft I6 serves as the input to gear box B during power drive. The forward end of intermediate shaft I6 is journaled in the bearing 20 that is associated with the torque converter lockvup clutch C, which clutch is subsequently described in detail. The rear end portion of intermediate shaft I6 is rotatably supported by a sleeve-type of bearing 4I that is mounted in the lixed sleeve unit 32 carried by the housing 42 of the transmission unit B.

The vaned guide wheels I'I and I8 are rotatably supported within the converter casing I3 by their hub portions I'Ia and Ita respectively. The hub portions I'Ia and Ia are rotatably mounted, by means of the one-way brake devices 2|, on the axially extending sleeve portion 32a of the xed sleeve unit 32 (see Fig. 1A). Sleeve unit 32 is fixed to and projects from the wall 42a of the relatively stationary, gear box housing 42. The one-way brakes 2I are arranged such that they will permit only forward rotary movement (clockwise when looking from the converter A towards the gear unit B) to be transmitted to the guide wheels Il and I8 by the rotation of the iiuid in the converter. The brakes 2I continuously prevent rotation of the guide wheels I'I and I8 in a reverse or counterclockwise direction when looking rearwardly from the front end of the converter A.

The torque converter unit A includes a gear type oil pump 25 having a driving gear 25a that is directly connected by nger and slot means 25h to the axially extending ange portion I3b of the rotatable converter casing I3. The pump 25 draws oil from a sump 26 and circulates it through the converter unit A, the transmission lubricating system, and the various hydraulically operated control mechanisms associated with this transmission unit (see Figs. 2 and 3). A second gear pump 84, driven by the transmission output shaft 8|, is also included in this transmission to provide a source of pressure fluid for the various hydraulically operated devices associated with the transmission unit. Rear pump 8.4 is operable even when the engine is not driving the pump 25. The operation of this pair of pumps driven by the input shaft'l 8 and output shaft 8| respectively is subsequently explained in greater detail.

In order to provide means for transmitting a positive, two-way, direct drive from the driving shaft 8 to the intermediate shaft i 6 a torque converter lock-up clutch C is provided. rIhe lock-up clutch C includes the radially extending drive transmitting disc 33 which has friction elements 33D mounted on its side faces adjacent its periphery. Drive transmitting disc 33 is drivingly connected by hubvportion 33a to the shaft i5 through the shaft hub member [a. Mounted between the disc 33 and the disc hub member 33a are several circumferentially extending, spaced, compression spring elements Sil (only one shown) that cushion the torque impact transmitted to the disc 33 on engagement of the clutch C. Springs 34 also serve to damp out vibrations of the disc 33. Springs M thereby facilitate smooth engagement of the clutch C. Pins 35 are arranged to extend between the disc 33 and the clutch disc anchor plate di) through enlarged openings in the hub member 33a. Pins 35 provide an additional means to connect the disc 33 and hub member 33a in the event of failure of the springs 3Q. Pins 35 also urge the disc 33 and anchor plate di against the sides of the hub member 33a and thereby tend to damp out vibrations of the disc 33. Coop- L eratively associated with the drive transmitting disc 33 is a driving plate 3S that is assembled as a part of the torque converter casing i3. Plate 3G has a piston bore 38a formed therein adjacent its periphery. .'Iounted within the piston bore 355e is an axially shiftable, hydraulically actuated annular piston 3l. Plate 35 also supports a clutch backing plate 38 which is arranged to cooperate with the piston 3l to provide means to clampingly engage the friction faces 33o therebetween and thus positively transmit drive between shafts 8 and i6 when pressure fluid is admitted to the piston bore 35a. Pressure fluid may be introduced to the bore 36a through the bore 39 in the clutch driving plate 35. Admission of pressure fluid to the piston bore 35a in plate 35 will move the piston 31 rearwardly so as to vengage the torque converter lock-up clutch C and directly connect the driving shaft S to the intermediate shaft I5. On release of the pressure iluid from the piston bore 36a. suitable spring means (not shown) and the pressure of the fluid within the converter casing I3 will urge the piston 37 forwardly to disengage the clutch C and provide a means for the transmission of a lluid transmitted, torque multiplying drive from shaft 3 through the fluid operated torque converter A to the associated intermediate driven shaft l5.

The gear box B includes the planetary gear trains 50, 50, which provide means for the transmission of torque multiplying reverse and forward drives respectively. The gear box housing 42 includes the forward wall portion 52a to which is connected by bolt means i3 a radially extending flange 32o of the axially extending hollow sleeve A member 32. The axially extending rear portion 32h of sleeve 32 provides a journal support for the planet pinion carrier member 5i of the reverse drive planetary gear train 50.

Reverse planetary gear train 5! includes the planet pinion carrier 5| which is formed with an axially extending peripheral drum portion 5|a adapted to be engaged by the braking band 52. Band 52 isactuated by servo unit 5S. Rotatably mounted on carrier 5l are a plurality of planet pinions 53, only one of which is shown in Fig. l. The teeth of planet pinions 53 drivingly mesh with the external teeth of the sun gear member 54. Sun gear member 54 is drivingly connected at itc to the rear end portion of the torque converter turbine driven shaft I6. rPhe teeth of planet pinions 53 are also in meshing engagement with the internal teeth `5 la formed on the drumlilre extension SIb of the planet carrier 6| of the forward drive planetary gear train 66. The drum member Sib, while forming the annulus gear of the reverse drive planetary gear train (if), is supported by and also forms a part of the planet carrier 3l of the forward drive planetary gear train 6G. Carrier 6l is drivingly connected to the output shaft 8l by the splines Bla.

Forward drive planetary gear train 6B includes the planet pinion carrier 6| which is splined to and supported by the output shaft 8l. Planet pinions 63 (only one shown), which are rotatably mounted on planet carrier El, have teeth meshingly engaged with internal teeth 54a on the rearwardly projecting drum-like flange portion 54h of sun gear 55 of the reverse drive planetary gear train 5B. This internally toothed portion 54h of the reverse drive planetary sun gear 54 thus forms the annulus gear of the forward drive planetary gear train 5G. The teeth of pinions 63 also meshingly engage external teeth on the sun gear '64 which gear is journaled on the axially extending sleeve 42o carried by the rearwardly located gear box housing wall LlZd. Sun gear 66 also mounts a brake drum engageable portion 64a. Braking band 62 is adapted to be applied to the peripheral portion of brake drum 64a to anchor the sun gear of the forward drive planetary gear train 60 against rotation. Band 62 is actuated by the servo unit B9.

It will be noted that the input to either of the planetary gear trains 5U or 6i) is always through the driven sun gear member 54 and associated flange 54h which gear member and associated flange 54D are drivingly connected at vHic to the intermediate driven shaft IB. The'output from either of the planetary gear trains 50 or G is always through the planet pinion carrier 6I which is splined to the output shaft 8|. Drive from sun gear 54 through the several planetary gear trains to the output shaft 3l is controlled by the application of the several braking bands 52, 62 of the planetary gear trains 5G, Bil, which bands are operated by the servo mechanisms 59 and 69 respectively. Y

In addition to providing a means for the transmission of a combination fluid and mechanically transmitted, torque multiplying, forward drive from shaft 8 through the series arranged torque converter A and the planetary gear train 6U to output shaft 8|, this transmission unit includes means whereby the planetary gear train 6U may be by-passed and a purely fluid generated, torque multiplying forward drive transmitted directly from the driving shaft 8 through the torque converter A to the output shaft 6|. The means for accomplishing this fluid transmitted and genei'at'ed, torque multiplying, forward drive includes the planetary direct drive clutch mechanism D. This planetary direct drive clutch D is arranged to directly connect the intermediate driven shaft I6 to the output shaft 8 I.

Clutch mechanism D includes the rotatable gear member` 64 having the pressure cylinder bore 'il formed therein. Bore 'il results from the dishlike shape 0f sun gear member 64 and its drumlike extensions 64b and 64a respectively. Reciprocably mounted in the cylinder bore 'il is the direct drive clutch actuating piston l2. Piston 1'2 is adapted to be moved forwardly by the admission of pressure iiuid to the cylinder bore il through the pressure iiuid inlet bores lll', i4. Piston member 'I2 has a nger portion 12a that is adapted to be moved into engagement with the axially movable clutch pressure plate t7 so as to clampingly and drivingly engage the clutch discs 65, 66 between the pressure plate 61 and the backing plate 63. Friction surfaced clutch discs 65 are drivingly mounted on the axially extending fiange Bic that projects from the pinion carrier 6 l. The cooperating clutch discs 65 are drivingly connected to the axially extending iiange 64a that forms a part of the sun gear 6d. When clutch discs 65 and 66 are drivingly engaged the planetary gear train 60 is locked up and a direct drive is transmitted from the input gear 54a and its driving shaft I6 to the output shaft 8i. rfhe pressure plate 67 and the backing plate 68 are both drivingly connected to the fiange portion 64a of the sun gear member 64 in conventional manner. A compression spring member 'i5 that extends between the piston 72 and a portion of the lsun gear 6d normally urges the piston 'i2 to its rearwardly positioned, clutch disengaged, position. The specific clutch construction herein disclosed includes centrifugal pressure compensating means to prevent accidental engagement of clutch D. The clutch D is specifically described and claimed in the co-pending application of Erik Quistgaard et al., Serial N-o. 140,456, filed January 25, 1950. In operation of the clutch mechanism D pressurized fiuid from the rear, output shaft driven, pump 84 is directed into the cylinder bore 'il through the inlet bores 14, 'M' to cause engagement of the clutch discs 65 and 66.

With the power transmission unit herein disclosed it is possible to initiate forward drive through either of two torque multiplying, drive ratios both of which are automatically convertible into a positive, two-way, direct drive. rlhe positive direct drive is not transmitted through the fluid of the torque converter A, therefore the slip of the torque converter is eliminated, thus an improved fuel economy as well as improved engine braking is available in the cruising direct drive range.

The two forward drive ratios available for initiating forward drive with this power transmission unit will for the sake of convenience be referred to as the Breakaway ratio and the Drive ratio. Breakaway ratio is normally used when an exceptionally fast getaway is desired as when crossing a busy intersection, or the like, Drive ratio is preferably used for all normal starting drive where the exceptionally fast Breakaway ratio acceleration is not absolutely necessary. However, even when starting through the Drive ratio the torque multiplying effect of the converter A is available for initiating drive and this accelerating effect is more than adequate to meet alll normal requirements.

When forward drive is to be initiated through the Drive ratio the torque converter 'lock-up clutch C is disengaged, the planetary direct drive` clutch D is engaged, and both brake bands 52 and 62 are in disengaged positions. With the power transmission unit so conditioned, as the engine driven shaft 8 is speeded up a hydraulically generated, torque multiplying drive is transmitted directly transmits this converter generated torque multiplying drive to the output shaft BI .by way of the planet carrier 6I of planetary gear train 66. The carrier member 6I is drivingly connected to output shaft 8l as previously described. Acceleration through this torque converter generated, torque multiplying ratio continues until certain output shaft speed and torque conditions are attained and then the transmission control system, that is subsequently described in detail, automatically effects engagement of the torque converter lock-up clutch C. Upon engagement of lock-up clutch C the driving shaft 8 is directly connected to the shaft IS, and as shaft I6 is directly connected to the output shaft 8| by the engaged direct drive clutch C, it is obvious that the power transmission unit is now positively transmitting drive at a 1:1 ratio through mechanically connected driving elements that will not normally slip during either power or coast drive or during engine braking. As the torque multiplication factor of the converter unit A is in the nature of 2 or 2.5 to l at stall, it is obvious that this ratio times the axle ratio of 3.3 or 3.9 to 1 gives an overall accelerating ratio of between 6.6'

to 9.8. Such overall ratios are more than adequate for normal acceleration with the powerful engines now used in motor vehicles.

Whenever forward drive is to be initiated through the Breakaway ratio the clutches C and D are initially disengaged and braking band 62 is applied to the drum portion 64a of the sun gear 6ft of forward drive planetary gear trains 6I). As the driving engine is speeded up todrive input shaft 8 at an increased speed, a combination fluid and mechanically generated, torque multiplying, underdrive is provided. This accelerating underdrive is from input shaft 8 through the torque converter A and the turbine driven intermediate hollow shaft i6 to the annulus gear portion 54a of gear member 5. As band 62 is applied, the driven annulus gear 54a drives the pinion carrier El of gear train 60 forwardly at a torque multiplying ratio. As the pinion carrier 6I is directly connected to the output shaft SI through the splines 8Ia a combination fluid and mechanically generated, torque multiplying underdrive is transmitted from converter A through forward drive,

train 60 to the output shaft 8| whenever drive is initiated through the Breakaway ratio. Acceleration through the combination iiuid and mechanically generated, torque multiplying, Breakaway drive train continues until certain output shaft speed and torque conditions are achieved and then the transmission control system, subsequently described in detail, causes the torque converter lock-up clutch C to be automatically engaged to provide for the direct transmission of drive from shaft 8 to shaft I6 to the input annulus gear 54a of the forward drive planetary B0. Acceleration after the converter clutch C is engaged is thereafter by way of the mechanical torque multiplying gear train 60. At some other predetermined conditions of output shaft speed and torque .thetransmission control system (Figs. 2 and .3) causes 4the band G2 to be disengaged and the planetary direct drve'clutch C to be applied to .then convert the mechanically generated, torque multiplying underdrive into a positively connected, two-way direct drive. Release of bandBZ and engagement of clutch YD provides lfor the transmission of a direct drive Vfrom input shaft 8 through clutch C to the intermediate driven shaft IB which latter shaft is directly connected to the output shaftil by'the direct drive clutch D. With the Breakaway drive ratio hereinabove described it is possible to get exceptional accelerating power for the torquemultiplication ratio of 2 or 2.5 to l or" the converter is combined with the torque multiplying ratio of approximately 1.5 of the planetary gear train 6i) and these ratios cornbine'with the axle ratio of 3.3 or 3.9 to l to give an overall ratio of between 9.9 and 14.7 .to 1. Itis thought to be 4quite obvious Vwhy the Breakaway ratio gives rocket-like acceleration when associated with one of thecurrent high powered motor vehicle engines.

Reverse drive may be obtained by applying brake band 52 to the drum portion 5 la of carrier member l of the reverse planetary ,gear train 50, the clutches C and D and band 62 being disengaged at this time. Drive from input shaft is then transmitted through the torque converter A to turbinedriven intermediate shaft i6. `Shaft I6 drives the'sun gear 54 of the reverse planetary train 59 forwardly whilefcarrier 5I is being held by brake band `52 therefore a combination fluid and mechanically transmitted torque multiplying reverse drive is transmitted to the annulus gear portion Gla of planet pinion carrier 6l. As carrier 6l is directly connected to the output shaft 8l, a combination uid and mechanically generated, torque multiplying reverse driveis transmittable from the input shaft'ii Athrough the converter A and gear train 5D to the output shaft 8|.

The controlsystem for operation of the several brakebands 52, 62 as wellfas the Vtorque converter lock-up clutch C and direct drive clutch D is diagrammatically shown in Figs. 2 and 3. f

Drivingly connected to theoutput shaft Si (seev Figs. l andS) by the pin'82 is a second gear type oil pump v84. Oil pump 34 is arranged to draw fluid from the oil sump through conduit 2S' and to circulate this pressurized fluid through y.

the torque converter Aandthe hydraulically operated control and lubrication systems of the transmissiony unit whenever vthe output shaftft is rotatingabove a certain speed. Consequently, pump v845 provides pressure fluid for operation of the transmission unit during a pushed or ltowed start even if engine driven pump 25 is inoperative due to the engine being ldead or the like. Suitable controls such as the arrangement shown in Figs. 2 and 3, and subsequently described in detail, are provided to insure thatpump 84 automatically takes over the supply of pressure-fluid for the transmission lunit control and lubricating.

systems whenever the speed of output shaft 8l exceeds a certain predetermined relatively low Value. This relieves the transmission driving engine of the load of front pump 25 afterthe engine unit has begun to drive the transmissionloutput shaft 8|.

Also drivingly mounted on the output shaft Bl (see Figs. 1 and 2 particularly) is a'speed responsive, centrifugal force operated, governor mechanism 85 which provides one of the means for automatically controlling operation of thistransmission unit. It isobvious thatvarious typesfof speedand ytorque responsive controls may be'used with this transmission but the speciiiogovernor mechanism S5 herein disclosed .is particularly advantageous due to its simplified design and novel manner of operation. Thisgovernorunit is arranged such that it does not require shaft driven gearing or electrically operated control units. Instead, this governor uses hydraulic pressure fluid supplied by the rear pump 84 Ain combination with the centrifugal force effect of a pair of output shaft mounted'telescopically arranged Weights 88, 89 for controlling actuation of the radially movable governor control valve 95 to provide a novel type ofl governor mechanism.

The governor 85 comprises the radially extending body portion 85 having a cylindrcal'bore 8'! extending radially inwardly from one end thereof. Reciprocably mounted in the bore 81 are the cylindrical primary and secondary weights 88 and 89 respectively, which weights are telescopcally arranged for 'movement relative to each other. Extending between the spaced apartend flanges on the weights 93 and 89 is a preloaded compression spring that tends to urge the weights 89 and 89 apart. A snap ring v9i mounted in the bore 81 of valve body 86 provides a seat for the primary weight when it is moved outwardly a predetermined distance by centrifugal force due to the rotation of Vdriven output shaft 8 l. Mounted in the bore in primary Weight d8 is a snap ring 92 that provides a seat for the secondary weight 89 on the primary weight 189, Extending through aligned bores in the secondary weight 89 and the driven output shaft 8l is a-tie shaft 9e that has one end suitably anchored to the secondary weight 89 by means of a.. snap ring or the like. The other end of tie shaft 94 has mounted thereon the piston type governor control valve 95, The governor valve 95 is arranged to reciprocate in the T-shaped bore 96 in the valve body 86. Governor piston valve 95 has spaced lands 95a and 95h of different diameters connected by a narrow neck portion 95e. -Extending through the valve lbody 85 transversely to bore A9S and intersecting bore 96 are the pressure fluid inlet and outlet passages `9'! and 98 respectively. Passage 91 is arranged to be connected by suitable conduit means 91' ktothe outlet from rear oil pump 84. The pressure fluidffrompump 84 is thusapplied through inlet passage 97 to the stem portion of valve -bore 96. The outlet passage 98 from the stem portion of the piston bore 9S is connected to an outlet conduit |93 (SeeFigs. 2 and 3). 'Ihe conduit l 63 conducts the pressure iiuid discharged from the piston valve bore 96 to the governor compensator ZIO that is subsequently described. Valve body 86 also in cludesa relief port i9! to relieve the excess pressure of the fluid in bore 96 of the governor unit 85. Relief port i9! also actsvasameans to vbalance Athe valve 95'in thebore 96 when it is acted on by the weights S8, Viili and the pressure fluid -in b ore .96. The valve body 8S is fixedly connected -to the driven voutput shaft 8l by the set screw 100. The governor tie shaft 915 is of such size as to be freely slidable in its shaft receiving bore through output shaft 8l and is not required to serve as a means for fastening the governor body 8G to vthe output shaft I The governor 85, which functions as Aa Vfluid pressure Vreducing valve, receives fluid under pressure from the rear pump 84 as soon as output shaft 8l begins to rotate. This pressure fluid from pump 84 is admitted to the valve bore :9 6 through the inlet passage 97 andl a hydraulic pressure is applied to the opposed inner surfaces of valve lands 95a, and 95h. As land 95h is larger in diameter than land 95a there is an unbalanced area which causes an unbalanced force to be applied to piston valve 95 which force tends to move valve 95 radially outward so as to cause valve land 95a to close oli the pressure iluid inlet passage 97. Due to the rotation of output shaft 3i there is also a simultaneously acting centrifugal force tending to urge the primary and secondary weights G8, 89 radially outward. As tie shaft 99 connects weights 88 and 89 to piston valve 95 it is obvious that the centrifugal force of the weights 88 and 89 and their connecting spring 99 is opposed by the hydraulic pressure applied to the unbalanced area of the piston valve land 95k. Consequently the centrifugal force of the elements 88, 99, 9i! tends to move valve 95 so as to uncover the passage 9'! and connect the pressure fluid inlet passage 9i to the valve bore 96 and outlet passage 98 while the unbalanced hydraulic force applied to piston valve land 95h tends to shift valve 95 in the opposite radial direction so as to'close off the connection between inlet passage 9'? and the valve bore 96 and outlet 99.

The pressure uid that is admitted to valve bore 96 is conducted through the outlet passage 98 to other parts of the control system to actuate the various control devices that are subsequently described in detail. If the pressure of the fluid admitted to the bore 95 from inlet 91 becomes excessive and exceeds the centrifugal force of the elements 38, 89, 90 then valve 95 will move radially outward a suicient amount to uncover the relief port IDI and the pressure liuid in the stem portion of bore 96 will spill out and reduce the pressure of the contained fluid to a value where a condition of equilibrium will again be set up between the centrifugal force of the elements 88, 89, 99 and the unbalanced force applied to the valve land 95e. A more complete description of the operation of this governor device 85 is set forth in the co-pending application of William L. Sheppard, Serial No. 98,493, led June 1l, 1949.

While the pressure of the fluid discharged from the pump B4 into the governor inlet passage 9'! is almost constant and also greater than the pressure of the uid discharged from the governor valve bore 96 into the outlet passage 98, due to the reducing valve action of piston valve 95, still, it is thought to be obvious that the pressure of the iluid discharged from the governor 85 is roughly proportional to the speed of the output shaft 8| and that governor 85 provides an efcient, sirnplified form of speed sensitive control mechanism. A

The control system (see Figs. 2 and 3) for this transmission includes the manually operable drive selector lever l I l which is rotatably mounted on the conventional motor vehicle steering column 2. Control lever is connected by suitable linkage H3 to the manually operable drive ratio selector valve |19. Valve Illl has five drive ratio positions which are presented in the drawings by the letters R, CO, BR, N and DR respectively. These letters correspond to the Reverse, Coast, Breakaway, Neutral and Drive ratios which ratios are selectively obtainable by manual shift of selector lever i I i. The letter V associated with the valve |10, and with the other valves of this control system, denotes a vent or drain port for returning pressure uid to the supply sump 2E. Pressure iluid from either of the supply pumps or 84 is directed into the main supply All) conduit 9| which is connected to and supplies pressure fluid to the manually operable drive ratio selector valve |10. The pressure of the iluid in conduit |9| is controlled by the pressure regulator valve |85. Check valves |83 and |84 maintain a closed pressure iiuid supply system. On admission of pressure fluid to the bore l'll of drive ratio selector valve |18 certain of the control mechanisms associated with the control system will be energized and one or the other of the several drive ratios will be activated as will be more fully eX- plained. When the manual valve |10 is located in the Neutral position the valve land l'lila closes off the port connecting supply conduit |9| to valve bore il! and obviously pressure uid cannot pass through valve |10 to activate any of the drive ratio selector' mechanisms. However, when the manually controlled valve |10 has been placed in the Neutral position and the vehicle engine is running or the vehicle is being pushed or towed so that one or the other of pumps 25 or 89 is operating, then pressure fluid will be directed through conduit |92 to the pressure regulator valve and through valve |85 to the conduit E93 that supplies pressure fluid to the converter A. Conduit |93 may contain a reduced portion |93a that acts as a ow control for the pressurized fluid directed into the converter A. Pressure iluid passing through converter A is returned to sump 29 and to the lubrication system by the conduit |94 that has associated therewith the converter pressure regulator valve |95 and the pressure fluid cooling unit |95. The converter pressure regulator valve |95 preferably maintains a pressure of approximately 40 to 50 p. s. i. in the converter so that the clutch C may be easily operated by normal line pressure of 80-90 p. s. i.

In any forward drive ratio position of the selector valve lll! pressure fluid from supply conduit i9! will always be directed through the supply port S of valve |19 and into the conduit H9 that connects the manual drive ratio selector` valve l 1|) with the torque regulating or torque responsive throttle valve |29. Consequently a torque responsive control is always available to cooperate with the speed responsive governor B5 to control automatic operation of this transmission unit in all forward drive ratios.

The torque responsive throttle valve |29 (see Figs. 2 and 3) has operably associated therewith the kickdown Valve 23| which is hereinafter described. The torque responsive throttle valve |29 is operated by the conventional throttle control or accelerator pedal ||5 for the engine unit (not shown) that drives this power transmission unit. Pedal l l5 is connected to the piston throttle valve l2! by the linkage H9. Throttle valve piston |2| is arranged to reciprocate in the bore |23 of the valve cylinder body |22 and is connected to the accelerator pedal ||5 through a compression spring |24, At closed throttle position of the acceleratorpedal H5 with the manual control valve i'lll set for any of the forward drive ratios denoted by CO, BR or DR, the arrangement of valve |29 is such as to pressurize conduit |25 and branch conduits |2511, |25?) and |250 with pump pressure iluid from supply conduits i9! and H9. Admission of pump pressure fluid to branch conduit |25a applies pressure fluid to the chamber 99h on the apply er on side of servo 69 and tends to cause application of brake band 92 to drum member 95a to condition the transmissionAfor the accelerating, combination fluid and mechanically generated, torque multiplying Breakaway underdrive. Torque converter lockup clutch C is disengaged at the beginning of all forward drive for the positions of throttle valve piston |2| and lock-up clutch shift valve piston at closed throttle are such as to prevent pressure fluid from conduits |25 and |2517` from entering conduit |56 to effect engagement of the converter lock-up clutch C. At closed throttle the land |2|a of throttle valve |2| is positioned so as to substantially close the pressure fiuid inlet port to valve bore |23 from supply conduit ||9 and prevent the pump pressure uid or socalled line pressure fluid (approximately 90 p. s. i.) in supply conduit H9 from being transmitted to the bore |23 of the valve cylinder |22. At closed throttle there is however suicient preload on spring |24 to shift valve |23 to the left a sufficient amount to permit seepage of a certain amount of pressure fluid from conduit H9 around valve land |2|a into bore |23 to develop about p. s. i. pressure in bore |23 and in the conduit |26 connected thereto. Branch conduit |26a connected to conduit |26 conducts pressure fluid to the chamber 55a on the apply side of servo 69 to assist in application of brake band |52. Branch conduit |25b that is also fed by conduit |26 communicates with the pressure chamber l43a at one end of the bore |43 in the cylinder body |41 of the direct clutch automatic control valve mechanism |1413. The seepage into conduit |26 from conduit |9through valve |2|! at closed throttle position of the throttle valve |2| transmits sufficient pressure fluid to the chamber |43a of the Valve to prevent the direct drive clutch D from being applied whenever the Breakaway drive ratio is used for initial acceleration. As the accelerator pedal ||5 is depressed from its closed throttle position to initiate vehicle acceleration the throttle valve |2| is moved to the left and this movement is transmitted by spring |24 to throttle valve |2| which latter valve is moved to the left a sufficient amount to uncover the line pressure .inlet port to bore |23 from supply oonduit H9 and admit pressure fluid from conduit ||9 to the bore |23 of the cylinder |22 and to supply conduit |26. The pressure fluid admitted to bore |23 from supply conduit H9. on partial depression of the accelerator pedal ||5 is of a lower pressure than the line pressure in conduit |9 due to the reducing valve action .of the valve land 2 la of the throttle valve |2|. The pressure of the fluid admitted to the bore |23. of valve |26 by the reducing valve action of valve land |2|a is hereafter referred to as throttle pressure. At wide open throttle with pedal |t|5 substantially depressed there is substantially a direct connection between conduit ||9 and the supply conduit |26 consequently the throttle pressure in conduit |25 will equal the line pressure in conduit |19. The admission of throttle pressure fluid to bore |23 of cylinder |22 has atendency .to shift the throttle valve |2| to the right to oppose depression of the accelerator pedal for it will be noted that a by-,pass bore |231; connects the main bore |23 with the chamber on the opposite side of valve land |2|@ so the throttle pressure fluid in bore |23 is applied to the left end of valve land |2| whereby throttle pressure reacts against the left end of throttle valve |2| and tends to urge the valve |2| to the right to balance the force being applied to the right end of valve |2| by the accelerator pedal |15.

rThe throttle pressure fluid admitted to conduits |26, |261) and to valve .chamber |4305 of the automatic control valve unit |40 for clutch D, during initial depression of the accelerator pedal |5, when valve |10 is set for a forward drive ratio such as Breakaway, applies throttle pressure to the chamber |43a at the left endof direct clutch shift valve |40 and to the chamber 553e at the left end of converter lock-up shift valve |60. The throttle pressure in chambers |43a and |6311 assists the springs |44 and |64 in urging shift valves |4| and |6| to positions towards the right end of Valve cylinders |6| and |62 as in Figure 2) which are the downshifted positions of the valves |4| and ISI. Thus during initial depression of accelerator pedal ||5 the valve lands |4|a and |5|a of shift valves |4| and |B| are positioned so that they cover the line pressure inlets from supply conduits |250 and |2511 to valve bores |43 and |63 respectively. This prevents line pressure from supply conduit |25 from passing through the clutch control valves |46 and |60l and into conduits |55 and |56 respectively to effect engagement of the converter lock-upvclutch C and the direct drive clutch D. Conduit |55 includesa branch conduit |551) that is adapted to transmit line pressure (approximately p. s. i.) to the chamber 69e on the band release or off side of the servo 69 that controls the forward drive planetary gearing 60. Thus it will be seen that the positions of the shift valves 54| and 46| control engagement and disengagement of the converter lock-up clutch C and the direct drive clutch D as well as the engagement and disengagement of the actuating brake band 62 of the forward drive planetary gearing 50.

Conduit |55 also includes a branch conduit |.55a that is connected to the direct drive clutch pressure compensator .unit |51. Compensator unit |51 is connectedto the bore 1| of the direct drive clutch D by the conduit |58. The pressure fluid that is passed through ,the compensator unit |51 is directed to clutch D by conduit |58 to engage the clutch D. The compensator |51 provides for the application of two different pressures to the direct drive clutch bore 1| depending on whether the transmission unit is set for the Drive ratio or the Breakaway ratio. When the drive ratio selector valve |10 is set for Drive then line pressure fluid of approximately 90 p. s. i. is conducted to the compensator |51 by conduit |55a after the direct clutch shift valve |4| has upshifted to the left. This line pressure of 90 p. s. i. in conduit |55a is applied to the right end of reciprocable valve |51a and it forces valve |51@ to the left to permit the line pressure in conduit |55c1. to pass through compensator |51 to the rconduit |58 and to clutch D to effectengagement thereof. Conduit |59 rdoes not contain pressure fluid when the transmission is set for Drive so there is no modification or compensation of the line pressure in conduit |5541. that is used to apply the clutch D when operating in the Drive ratio. However, when the manual drive ratio selector valve |10 is set for Breakaway then .the conduit |59 contains line pressure and when the direct clutch shift valve |4| upshifts, the line pressure in conduit |5511 urging valve |51a to the left is opposed by a lesser, compensated pressure in chamber |511) of valve |51. The pressure in chamber |5113 results from the bleeding of line pressure from conduit |59 to the chamber |5117 through valve bore |510 as the valve |510- is moved to the left and cracked open to permit line presure from conduit |59 to enter the bore |51d of thecompensator unit |51. The compensator unit 51 thus acts as. a pressure reducing valve when the selector 'valve |10 is set for Breakaway and it directs. a compensated pressure fluid with a maximum pressure of approximately 80 p. s. i. to the clutch D to effect engagement thereof when operating in the Breakaway ratio. The reason these two diierent clutch applying pressures are used to effect engagement of clutch D when operating in the Drive and Breakaway ratios is that when the transmission is set for Drive ratio the clutch D is engaged at the time drive is initiated and therefore clutch D must transmit the full torque multiplication of the converter A which may be as much as three times the direct drive torque. Accordingly, the higher applying pressure, that is full line pressure (90 p. s. i.), is used to apply clutch D during drive through the Drive ratio. However, when the selector valve is set for initiation of drive through the Breakaway ratio, the clutch D is not applied until after the torque converter has been locked-up by the engagement of clutch C so the direct drive clutch D is not required to transmit f -a multiplied torque drive and thus a somewhat reduced line pressure of about 80 p. s. i. or less is now adequate to engage the clutch D. The reduced clutch applying pressure tends to give smoother clutch operation therefore it is quite advantageous.

After the drive ratio selector valve 10 has been moved from the Neutral position to the selected Drive or Breakaway position for initiating forward drive, the control valving will have applied i the appropriate clutches and/or bands and then depression of the accelerator pedal |55 will cause drive to be transmitted to the output shaft 8|. Obviously until the initiation of drive, the governor 85 is not providing a speed responsive controlled governor pressure iiuid for the conduit |03 so the clutch control valves |4| and IGI are in their downshifted positions at the right sides of the control valve units and |00 respectively, as shown in Figs. 2 and 3. Until a pressure fluid such as governor pressure is applied to the right ends of the pilot valves and |04 the shift valves |4| and |6| cannot be shifted to the left to their upshifted positions. However, as the output shaft 8| begins to gain speed, due to depression of accelerator H5, a variable governor pressure is directed to the governor pressure supply conduit |03 and this governor pressure in conduit |03 will attempt to bring about the upshift of the clutch shift control valves |4| and |6I. This governor pressure in conduit |03 will tend to apply a uid pressure generated upshifting force to the right end of each ofthe clutch pilot valves |45 and |65. Pilot valves |45 and |65 are reciprocably mounted in the bores |46 and of valve units |40 and |00 and are adapted to be moved leftwardly into engagement with the shift valves 4| and |0| to effect upshift of valves |4| and 55| towards the left. 'Due to the governor pressure compensator 2i0 and its associated selector valve 220 it is possible to apply different pressures to the chambers |4Ba and |05a at the right end of valves |40 and |00 and thus have different points of engagement for the converter lock-up clutch C and the direct drive clutch D when drive is initiated through the Breakaway drive ratio. rlhis is necessary when the transmission is set for the Breakaway forward drive ratio for it is advantageous to have the torque converter clutch C lock-up the torque converter at a lower vehicle speed than that which eects lock-up of the direct drive clutch D of the planetary gearing 60. By this arrangement a step-by-step upshift from a drive-"train cornprising converter A plus gear train 00, to the gear '14 train 60 alone, to direct drive in three unnoticed steps is obtainable.

The governor pressure compensator 2|0 functions similarly to the direct clutch compensator |51 in that it modifies the line pressure transmitted to the compensator 2 0 by the conduit 200. Instead of applying governor pressure from conduit |03 directly to the chamber |06a at the right end of converter lock-up clutch control valve |60, it is possible, by virtue of the compensator 2|0 and valve 220, to apply either governor pressure or a higher modulated pressure that is proportional to the governor pressure, to the chamber |66a of converter clutch control valve |60. These two different pressures that are applied to the pilot valve |05 of valve |00 bring about two different points at which the converter lock-up clutch C will be engaged depending on whether the manual drive ratio selector valve |10 is set for the Breakaway ratio or the normal forward starting Drive ratio. The reason for the two different engagement points of converter lock-up clutch C is that when the transmission is set for Drive the complete torque multiplication of the power transmission unit must be supplied by the converter A, as the gear box B has the torque multiplying gearing 60 locked up during the Drive ratio. Accordingly, the converter A must be active over a longer period of time in the Drive ratio than when the transmission is set for the Breakaway ratio where the gearing 00 will provide some torque multiplication even after the converter A has been locked up by engagement f of the clutch C. Thus a relatively low pressure,

that is, direct governor pressure is applied to the pilot valve of converter clutch control valve unit |00 to effect leftward shift thereof when operating in the Drive ratio Whereas when operating in the Breakaway ratio the compensator 220 applies a relatively high compensated line pressure from conduit 209 to the pilot valve |65 to effect upshift thereof. Obviously when the higher compensated pressure is applied to valve |65, the upshift to lock-up converter clutch C will occur at a lower vehicle speed than when the lower governor pressure is used to effect th lock-up of converter clutch C.

A brief description at this point of the compensator 2|0 and the associated valve 220 will undoubtedly facilitate an understanding of the aforementioned operation of the control system for this transmission in the several forward drive ratios. When manually operable drive ratio selector valve |10 is set for initiating drive f through through the Drive ratio then valve |10 admits line pressure fluid (approx. p. s. i.) from v supply conduit |0| to conduits ||9 and 2|0. Line pressure fluid in conduit H9 passes through the throttle valve |20 to the left end of valves |40 and |60 as previously explained. Line pressure from conduit ||0 can pass through valves |40 and |51 to apply the direct clutch D and release band 02 of planetary 00 to condition the transmission for the Drive ratio as previously explained if shift valve |4| has been upshifted to the left. The line pressure fluid admitted to conduit 2|9 when the transmission is set for the Drive ratio enters the valve 220 and forces the floating ball element 22| to the left so that the line pressure fluid in conduit 2|9 may pass from conduit 2|0 through valve 220 and into conduit 222 which directs it into chamber |46a of valve |40. Line pressure in chamber |40a, is applied to the right end of the pilot valve |45 and this shifts the pilot valve |45 and the direct clutch shift valve 14| to' the left and admits4 line pressure from conduits |55', |58

to the piston bore of the direct clutch D to effect engagement thereof. Accordingly the planetary gearing B will be locked out of all drive when operating in the Drive ratio and the drive train is directly from the torque converter A to output shaftl 8| as previously explained. With line pressurein conduit 2|9 and the ball element 22| of valve 228 closing the pressure fluid inlet port at the left end of valve 220, the governor pressure, which varies from approximately 0-90 p. s. i. depending on the speed of output shaft 8|, will pass from conduit |03 through the governor pressure compensator 25D and into conduit 223 which directs the governor pressure fluid into chamber IGGa at the right end of converter clutch ycontrol valve |60. Governor pressurey uid in chamber E'oa `of valve |60 tends to urge the pilot valve |65 and converter lock-up clutch shift valve IBI towards the left to effect lock-up of the converter C. As throttle pressure, which varies from 0-99 p. s. i. is already being directed into the chamber |6311 at the left end of control valve |53, it is obvious that shift valve |6| will not shift over to the left to effect engagement of converter lock-up clutch C until after the governor pressure in chamber |65@ exerts a greater leftwardly directed force on shift valve IBI than the rightwardly directed force of the throttle pressure in chamber l'a. It will be noted that the diameter of the pilot valve V is greater than the diameter of the shift valve |51 therefore when the throttle pressure in chamber |63a is equal to the governor pressure in chamber |66a, still a shift .of valve to the left will occur. Once the valves Ai 6| and |65 begin to shift towards theV left then the by-pass conduit |25@ transfers throttle pressure to the right side of valve land 155e of pilot valve |65 and a snap-action upshift is eifected that prevents hunting of the valves 45| and |65 and provides a very definite engagement point for the converter lock-up clutch C. 'This particular snap action valve control is more fully explained in the co-pending application of William L. Sheppard, Serial No. 98,493, filed June 1 11, 1949. It is thought to be obvious that once shift valve ISI moves to the left that then line pressure from conduit |251) can pass through valve bore |63 of valve |60 and into conduit |55 which directs this line pressure fluid into the l converter lock-up clutch C' to effect engagement of clutch C. From the description above it is thought to be apparent that the torque responsive throttle pressure in chamber |63a of control valve |66 and the speed responsive governor pressure in the chamber |66a of valve l conjointly control the automatic engagement and disengagement of the converter lock-up clutch C. Obviously the points for lock-up of the clutch C will vary depending on the particular vrelationship existing between the Vspeed and torque conditions of the output shaft 8|. When operating in the Drive ratio at Wide open throttle, that is with a large torque load on shaft 8|, the lock-up of clutch C might not occur until the vehicle speed has reached 45-50 miles per hour, whereas at light throttle under a light torque load, the clutch C could be automatically engaged at about 17 miles per hour vehicle speed. The automatic disengagement of clutch C would normally occur when the vehicle speedhas been reduced to approximately l0-15 miles per hour.` The lvarious shift pointscanbeadiusted tome-,et the particular desires of the operator. by making certain 16 changes in the valving that are thought to be rather obvious.

If while operating in the Drive ratio at a relatively highvehicle speed and/or light torque load such that the clutch C is engaged and the transmission is transmitting the positive direct drive, the vehicle operator should desire to accelerate in a torque multiplying ratio, it is merely necessary for the operator to fully depress the accelerator pedal ||5 and thisv will manually overrule the automatic control of the clutch C and disengage the lock-up clutch C so that the converter A is then brought back into operation to provide a torque multiplying drive. This manual kickdown from the positive direct drive to a torque multiplying drive ratio is accomplished by means of the kickdown valve 230 and its associated elements which are controlled by the accelerator pedal H5. Linkage ||G of the accelerator ||5 carries a finger-like projection ||'1` that is adapted to be engaged with the neck-like projection 2Std on the right end of the piston valve 23| of the valve unit 230, after a predetermined depression of the accelerator H5. As accelerator H5 is fully depressed, the last 5 or l0 degrees of its downward throttle valve opening movement causes the finger-like linkage projection to engage the projection 23la on valve 23| and shift the kickdown valve 23| to the left. Movement of valve 23| to the left connects the pressure iiuid in conduits 232 and 233 through the relief valve 23d and this reduces the forces holding valve |6i in the upshifted position. This permits the pilot valve |55 and shift valve |6| for the torque converter lock-up clutch C to downshift to the right to effect disengagement of the clutch C and to simultaneously activate the converter A. The shift to the right of valves ISI and |65 is accelerated by the increased throttle pressure applied to the chamber |6311 at the left end of valve IE5 due to the full depression of the accelerator H5. Obviously, on release of the accelerator ||5 the spring 235 of lrickdown valve unit 23D will shift valve 23i to the right to its normally inactive position and the transmission control system will be returned to its automatically controllable condition.

On manual kickdown with the drive ratio selector lever HE! set for'the Drive ratio, it will be noted that the leftward shift -of kickdown valve 23E permits conduits 242 and 243 to be connected to the relief valve 244. This reduces the force holding the direct clutch shift valves |4| and |6| in their upshifted or leftward positions but due to the line pressure applied to the chamber |4611 at the right end of valve |40, when the transmission is set for Drive, the shift valve |4| and pilot valve |45 are held in their upshifted positions even though the pressure in conduits 242 and 243 is reduced. This maintains the transmission in the selected Drive ratio with direct clutch D engaged.

If the manually operable drive ratio selector lever is set for initiating drive in the Breakaway drive ratio then line pressure fluid of approximately p. s. i. will be directed from supply conduit |9| into conduits 9, |59 and 209 respectively. Line pressure that is directed into conduit ||9 passes through the throttle valve |2D from whence line pressure is directed by conduits l25a and |252) to the servo 69 and the valves |4 and |69 respectively. Servo 69 is thuscaused to apply the band 62 and this .activates seal' train 6D for the transmission of a torque-,multiplying underdrive. The line pressure uid in conduit |25p remains inactive until the valves ISI and |d| are successively upshifted towards the left to eiect step-by-step engagement of the converter lock-up clutch C and the direct drive clutch D. The successive step-by-step engagement oi the clutches C and D is brought about by the line pressure iluid admitted to conduit 269 when the drive ratio selector valve Vit is set for Breakaway drive. Line pressure in conduit 209 is directed to the governor compensator unit 2|!) and is modulated by the compensator 2| so that a variable pressure of between 15-90 p. s. i. is passed through the compensator Zi to the conduit 223 and into the chamber |66a at the right end of converter lockup clutch control valve |63. The modulated pressure transmitted through compensator 2| to conduit 223 and the pilot valve it for the converter lock-up clutch C is directly proportional to but greater than the governor pressure which exists in the conduit |53 at all vehicle speeds above approximately 8-10 miles per hour. With valve i'i set for Breakaway the conduit 2|9 is not pressurized with line pressure and the governor pressure (-90 p. s. i.) in conduit H33 will force the ball element 22| of valve 220 to the right so that governor pressure can pass from conduit ||3 through valve 22 into conduit 222 and be applied to the right end of pilot valve |65 of the direct clutch control valve |50. Thus in the Breakaway ratio throttle pressure (0-90 p. s. i.) is applied to the left ends of shift valves |l| and |5| while governor pressure and an increased, compensated governor pressure are applied to the right ends of the pilot valves |45 and |65 respectively. As the compensated governor pressure applied to pilot valve |65 is greater in value that the governor pressure applied to pilot valve M5, the shift valve ll will be upshifted to the left to eiiect engagement of converter lock-up clutch C' at a lower vehicle speed than the speed at which the shift valve |l|| is upshifted to the left to eiect engagement of the direct drive clutch D. This causes lock-up of the converter C first and thereafter release of gear brake band 62 and engagement of clutch D so as to give the two step upshift to the positive direct drive from the combination fluid and mechanically generated, torque multiplying Breakaway starting drive.

While traveling in the positively connected direct drive ratio with the drive ratio selector valve Sie set for Breakaway, the vehicle operator can also manually or otherwise overrule the automatic control system and kickdown to a torque multiplying underdrive ratio at any time the vehicle speed is below approximately 50 miles per hour. The kickdown is effected in the same manner as already explained with regard to the kickdown when traveling in the Drive ratio. A full depression of accelerator pedal lid will cause lever i'! to shift kickdown valve 23| to the left and this will connect conduits 232 and 233 to relief Valve 234i while conduits 242 and 243 are connected to relief valve 245, Reduction of the throttle pressurn in conduits 242 and Edil permits direct clutch shift valve lill and pilot valve M5 to shift to the right to effect release of clutch D and to simultaneously engage the brake band 62 of planetary gearing 5@ through actuation of the servo Si. This conditions the transmission gear box B for the torque multiplyine underdrive ratio. The reduction of the pressure of the iiuid in conduits 23'2 and 233 by their connection tc relief valve 234 on leftward shift of kickdown valve 23|, when the transmission is set for Breakaway, is not a suiclent pressure reduction to overcome the eifect of the relatively high compensated pressure in chamber |6511 of converter clutch control valve |60. Accordingly, converter lock-up clutch shift and pilot valves |6| and |65 do not downshift to the right thus the converter lock-up clutch C remains engaged at all vehicle speed above 20-25 miles per hour and the kickdown in Breakaway is to a positively connected underdrive drive train that does not pass through the fluid of the torque converter. Due to this fact there is no slip in this kickdown ratio as might be the case with a kickdown through the torque converter and a positively connected gear train for acceleration as well as coast braking is available. Upon release of the accelerator i l5 it is obvious that the automatic speed and torque responsive controls of the transmission will immediately take over operation of the transmission unit.

In the operation of this transmission in the Breakaway ratio the shift points are somewhat different from those when operating in the Drive ratio for the converter A does not have to remain engaged for as long a time due to the gear train Ee being available to provide a part of the torque multiplication. As a result of the geai' train 58 operating in series with the torque converter A when the transmission is set for the Breakaway ratio, the speed of the output shaft 8| is accelerated at a greater rate than when the transmission is set for the Drive ratio and at the same time the speed of the engine driving the transmission will increase at a greater rate when Operating in the Breakaway ratio than in the Drive ratio. Accordingly, the torque multiplication of the converter A ceases at a lower vehicle speed when operating in the Breakaway ratio than when operating in the Drive ratio. At wide open throttle the torque converter lock-up clutch C might engage at 25-30 miles per hour vehicle speed and the direct drive clutch D would engage at approximately 50-55 miles per hour vehicle speed when operating in the Breakaway ratio. At light throttle or low torque load the converter lock-up clutch C might engage at 13- 15 miles per hour and the direct drive clutch D might engage at 18-20. At light throttle, automatic disengagement of the direct drive clutch D would occur at approximately 13 miles per hour vehicle speed while the converter lock-up clutch C would be disengaged at about 11 miles per hour. However, on coast drive at closed throttle, when the vehicle speed has been reduced to approximately 10-15 miles per hour, then the lock-up clutch C will disengage before the direct drive clutch D and this gives a fluid drive cushion for the disengagement of the direct drive clutch D and prevents jerks or the like.

If while operating in either the Drive ratio or the Breakaway ratio, it should become advantageous or necessary to employ a coasting gear for coast braking, it is merely necessary for the operator to manually or otherwise move the drive ratio selector lever to the Coast position. This conditions the transmission for the same ratio that is also obtained by a kickdown from direct drive when operating in Breakaway. The converter lock-up clutch C will be applied, direct drive clutch D will be disengaged, and brake band S2 will be applied by servo 69 so that a positively connected underdrive ratio is available for the coast braking. This ratio will not slip and it will provide an adequate braking effeet on coast drive. The Coast ratio may be manually shifted back into either of the forward drive ratios when the coast braking effect is no longer required. In the Coast ratio the control valving is set substantially the same as with the Breakaway ratio for the selector valve il still admits line pressure from supply conduit |9| to conduits H5, |59 and 259. In addition line pressure is now admitted to coast conduit 25S which conducts this pressure huid to chamber |48 of the direct drive clutch valve itil. Line pressure in chamber |48 of valve M3 forces pilot valve |45 to shift to the right and this insures that shift valve |4| will be held in al downshifted position so as to maintain the direct drive clutch D in its disengaged position and cause application of the brake band 52 to thereby actuate the underdrive gear train 65.? for coast braking.

Reverse drive is obtainable by shifting the manually operable drive ratio selector valve Sie to the Reverse position. This pressurizes conduits |59, 269, 259, 258, 269 and 2li! with pressure fluid from supply conduit l9|. Pressure iluid in conduits |59, 259 and 259 remains inactive however. Due to pressure fluid entering conduit 269 the pressure regulator valve E65 now establishes a line pressure of approximately 1,80 p. s. i. in the control system instead of the 9G p. s. i. that is utilized for the forward drive ratios The increased pressure in the control system during Reverse drive is advantageous because of the increase torque reaction when operating in the 2 :1 Reverse drive ratio. The conduit 210 conducts increased line pressure fluid to the chamber 59a of the reverse gear train servo 59 to apply reverse brake band 52 and condition the planetary gearing 5D for the transmission of a torque multiplying Reverse drive from the converter A to the output shaft 8|. As the control system for the clutches C and D as well as the forward drive servo 69 are not pressurized it is thought to be obvious that there is no auto-- matic upshifting or downshifting when operating in the Reverse drive ratio.

It is thought to be obvious from the foregoing description that there is provided an improved, highly flexible, simplied type of motor vehicle power transmission unit that provides all the necessary gear ratios and control features for maximum performance and driving comfort and yet permits manufacture and assembly at an economical gure.

I claim:

1. An engine driven power transmission unit comprising a driving member, a hydrokinetic torque converter including an impeller wheel drivingly connected to the driving member, a runner wheel, a guide wheel, and converter lockup clutch means adapted to mechanically connect the impeller and runner wheels, a gear box including an input shaft drivingly connected to the runner wheel, an output shaft, a planetary gear train adapted to be drivingly connected between said input and output shafts comprising an annulus gear drivingly connected to the input shaft, a sun gear concentrically and rotatably mounted with respect to said annulus gear, brake means adapted to anchor Daid sun gear against rotation, a planet pinion carrier drivingly connected to said output shaft, a planet pinion rotatably mounted on said planet pinion carrier and arranged in meshing engagement with said annulus gear and said sun gear, and a direct drive clutch means for said planetary gear train adapted to drivingly connect said carrier and sun gear, and control means for said converter clutch, planetary bralreand direct drive clutch including output shaft speed responsive and engine torque responsive control valving to automatically lcontrol the engagement and disengagement of said converter lock-up clutch means and said planetary brake means and direct drive clutch means, said control means being arranged to selectively provide a first starting underdrive ratio from said driving member through said converter and activated gear train to said output shaft and a second starting direct drive ratio from said driving member through said converter and the engaged direct drive clutch to said output shaft, said control means being adapted to automatically upshift each oi said starting -drive ratios to a positiveiy connected, one-to-one, direct drive ratio from said driving member to said output shaft.

2. An engine driven power transmission unit comprising a driving member, a hydrokinetic torque converter including an impeller wiiee drivingly connected to the driving member, a runner wheel, a guide wheel, and converter loci;- up clutch means adapted to be operated to positively connect the impeller and runner wheels, a gear box including an input shaft drivingly connected to the runner wheel, an output shaft, a planetary gear train adapted to be drivingly connected between said input and output shafts comprising an annulus gear drivingly connected to the input shaft, a sun gear concentrically and Yrotatably mounted with respect to said annulus gear, brake means adapted to anchor said sun gear against rotation, a planet pinion carrier drivingly connected to said output shaft, a planet pinion rotatably mounted on said planet pinion carrier and arranged in meshing engagement with said annulus gear and said sun gear, and a direct drive clutch means for said planetary gear train adapted to drivingly connect said carrier and sun gear, and control means comprising output shaft speed responsive and engine torque responsive control valving to automatically control the engagement and disengagement of said converter lock-up clutch means and said planetary brake means and direct drive clutch means, said control means being arranged to selectively provide a rst starting undcrdrive ratio from said driving member through said converter and activated gear train to said output shaft and a second starting direct drive ratio from said driving member through said converter and the engaged direct drive clutch to said output shaft, said control means being adapted to automatically upshift each of said starting drive ratios to a positively connected, one-to-one, direct drive ratio from said driving member to said output shaft, said control means for said several clutch means being arranged to effect successive engagement or said converter clutch means and then the direct drive clutch means on the upshift to direct drive when operating in the first starting drive and to normally eifect successive disengagement of the direct drive clutch and then the converter clutch means on the downshift from direct drive when operating in the rst starting drive ratio.

3. An engine driven power transmission unit comprising a driving member, a hydrokinetic torque converter including an impeller wheel drivingly connected to the driving member, a runner wheel, a, guide wheel, and converter lockup clutch means adapted to be operated to positively connect the impeller and runner wheels, a gear box including an input shaft drivingly connected to the runner wheel, an output shaft, a planetary gear train adapted to be drivingly connected between said input and output shafts comprising an annulus gear drivingly connected to the input shaft, a sun gear concentrically and rotatably mounted with respect to said annulus gear, brake means adapted to anchor said sun gear against rotation, a planet pinion carrier drivingly connected to said output shaft, a planet pinion rotatably mounted on said planet pinion carrier and arranged in meshing engagement with said annulus gear and said sun gear, and a direct drive clutch means for said planetary gear train adapted to drivingly connect said carrier and sun gear, manually operable control means to select the starting drive ratios by operation of said clutch and brake means and control means comprising output shaft speed responsive and engine torque responsive control valving to automatically control the engagement and disengagement of said converter lock-up clutch means and said planetary brake means and direct drive clutch means, and driver operable output shaft torque control means adapted to manually overrule the automatically operable control means for the several clutch means said control means being arranged to selectively provide a rst starting underdrive ratio from said driving member through said converter and activated gear train to said output shaft and a second starting direct drive ratio from said driving member through said converter and the engaged direct drive clutch to said output shaft, said control means being adapted to automatically upshift each of said starting drive ratios to a positively connected, cne-to-one, direct drive ratio from said driving member to said output shaft, said driver operable output shaft torque control means providing means to downshift the transmission from the positively connected, one-to-cne direct drive ratio to either of preselected starting drive ratios.

4. A power transmission unit comprising a driving member, a hydrokinetic torque converter including an impeller wheel drivingly connected to the driving member, a runner wheel, a guide wheel, and converter lock-up clutch means adapted to be operated to positively connect the impeller and runner wheels, a gear box including an input shaft drivingly connected to the runner wheel, an output shaft, a planetary gear train adapted to be drivingly connected between said input and output shafts comprising an annulus gear drivingly connected to the input shaft, a sun gear concentrically and rotatably mounted with respect to said annulus gear, brake means adapted to anchor said sun gear against rotation, a planet pinion carrier drivingly connected to said output shaft, a planet pinion rotatably mounted on said planet pinion carrier and arranged in meshing engagement with said annulus gear and said sun gear, and a direct drive clutch means for said planetary gear train adapted to drivingly connect said carrier and sun gear and control means comprising output shaft speed torque responsive control devices to automatically control the engagement and disengagement of said converter lock-up clutch means and said planetary brake means and direct drive clutch means said control means being arranged to selectively provide a first starting underdrive ratio from said driving member through said converter and activated gear train to said output shaft and a second starting direct drive ratio from said driving member' through said converter and the engaged direct drive clutch to said output shaft, said control means being adapted to automatically upshift each of said starting drive ratios to a positively connected, one-to-one,

direct drive ratio from said driving member to said output shaft, a rst driver operable control means adapted to vary the torque of the output shaft and providing a means to manually overrule the automatically operable control means for the converter lock-up clutch means and the direct drive clutch means whereby said several clutch means my be disengaged at the will of the operator and a positive one-to-one direct drive downshifted to the preselected starting drive ratio, and a second driver operable control means to manually disengage said direct drive clutch means and to maintain said direct drive clutch means disengaged irrespective of the torque and speed condition of the output shaft so as to maintain said transmission in an underdrive ratio through said planetary gear train.

5. A power transmission unit for a motor vehicle having an engine, an accelerator control therefor, and a transmission drive ratio selector lever, said power transmission unit comprising a hydrokinetic torque converter including an impeller wheel drivingly connected to the engine, a runner wheel, a guide wheel, and converter lockup clutch means adapted to positively connect the impeller and runner wheels, a gear box including an input shaft drivingly connected to the runner wheel, an output shaft, a planetary gear train adapted to be drivingly connected between said input nad output shafts comprising an an nulus gear drivingly connected to the input shaft, a sun gear concentrically and rotatably mounted with respect to said annulus gear, brake means adapted to anchor said sun gear against rotation, a planet pinion carrier drivingly connected to said output shaft, a planet pinion rotatably mounted on said planet pinion carrier and arranged in meshing engagement with said annulus gear and said sun gear and a planetary direct drive clutch means adapted to drivingly connect said carrier and said sun gear to provide for a direct one-to-one drive through said planetaryT gear train, control means operable by said drive ratio selector lever to selectively condition said power transmission unit for a first starting, torque multiplying, direct drive from said engine through said converter and engaged direct drive clutch to said output shaft and for a second starting, torque multiplying, underdrive from said engine through the series arranged converter activated planetary gear train to said output shaft, said control means including output shaft speed re sponsive and engine torque responsive control means adapted to automatically operate said clutch and brake means to thereby provide means to automatically upshift either of the pre-selected starting drives to a positively connected, one-toone, direct drive from the engine to the output shaft and to automatically downshift the positively connected, one-to-one, direct drive to the preselected starting drive with changes in the output shaft speed and engine torque.

6. A power transmission unit for a motor vehi cle having an engine, an accelerator control therefor, and a transmission drive ratio selector lever, said power transmission unit comprising a hydrokinetic torque converter including an impeller wheel drivingly connected to the engine, a runner wheel, a guide wheel, and converter lockup clutch means adapted to be engaged to positively connect the impeller and runner wheels, a gear box including an input shaft drivingly connected to the runner wheel, an output shaft, a planetary gear train adapted to be drivingly connected between said input and output shafts comprising an annulus gear drivingly connected to the input shaft, a sun gear concentrically and rotatably mounted with respect to said annulus gear, brake means adapted to anchor said sun gear against rotation, a planet p-inion carrier drivingly connected to said output shaft, a planet pinion rotatably mounted on said planet pinion carrier and arranged in meshing engagement with said annulus gear and said sun gear and a planetary direct drive clutch means adapted to drivingly connect said carrier and said sun gear to provide for transmission of a one-to-one direct drive by said planetary gear train, control means operable by said drive ratio selector lever to selectively condition said power transmission unit for a first starting, torque multiplying, direct drive from said engine through said converter and engaged direct drive clutch to said output shaft and for a second starting, torque multiplying, underdrive from said engine through the series arranged converter and activated planetary gear train to said output shaft, said control means including output shaft speed and torque responsive control valving adapted to automatically operate said clutch and brake means to thereby provide means to automatically upshift either of the preselected starting drives to a positively connected, one-to-one, direct drive from the engine to the output shaft and to automatically downshift the positively connected, one-to-one direct drive to the pre-selected starting drive with changes in the output shaft speed and engine torque, and driver operable accelerator controlled means to overrule the automatic downshifting of said positively connected, one-to-one, direct drive to the pre-selected torque multiplying starting drive tov thereby provide for such a downshift at the will of the vehicle operator.

7. A power transmission unit for a motor vehicle having an engine, an accelerator control therefor, and a transmission drive ratio selector lever, said power transmission unit comprising a hydrokinetic torque converter including an impeller wheel drivingly connected to the engine, a runner wheel, a guide wheel, and converter lock-up clutch means adapted to be engaged to positively connect the impeller and runner wheels, a gear box including an input shaft drivingly connected to the runner Wheel, an output shaft, a planetary gear train adapted to be drivingly connected between said input and output shafts comprising an annulus gear drivingly connected to the input shaft, a sun gear concentrically and rotatably mounted with respect to said annulus gear, brake means adapted to anchor said sun gear against rotation, a planet pinion carrier drivingly connected to said output shaft, a planet pinion rotatably1 mounted on said planet pinion carrier and arranged in meshing engagement with said annulus gear and said sun gear and a planetary direct drive clutch means adapted to drivingly connect said carrier and said sun gear to provide means for the transmission of a positive, one-to-one, direct drive by said gear train, control means operable by said drive ratio selector lever to selectively condition said power transmission unit for a first starting, torque multiplying, direct drive from said engine through said converter and engaged direct drive clutch to said output shaft and for a second starting, torque multiplying, underdrive from said engine through the series arranged converter and activated planetary gear train to said output shaft, and said control means including output shaft speed and torque responsive control valving adapted to automatically operate said clutch and brake means to thereby provide means to automatically upshift either of the pre-selected starting drives to a positively connected, one-to-one, direct drive from the engine to the output shaft and to automatically downshift the positively connected, one-to-one, direct drive to the pre-selected starting drive with changes in the output shaft speed and engine torque, and driver operable accelerator controlled means to overrule the automatic downshifting of said positively connected, one-to-one, direct drive to the pre-selected torque multiplying starting drive to thereby provide for such a downshift at the will of the vehicle operator, and drive ratio selector lever operated means to downshift said positively connected, one-to-one, direct drive to a torque multiplying positively connected, underdrive that will be maintained regardless of variations in the output shaft speed and engine torque.

8. A power transmission unit comprising a driving member, a hydrokinetic torque converter including an impeller wheel drivingly connected to the driving member, a runner Wheel, a guide wheel, and converter lock-up clutch means adapted to be engaged to positively connect the impeller and runner wheels, a gear box including an input shaft drivingly connected to the runner wheel, an output shaft, a planetary gear train adapted to be activated to be drivingly connected between said input and output shafts to provide for the transmission of a first starting torque multiplying underdrive therebetween, and planetary direct drive clutch means adapted to lock up said planetary gear train and be engaged to prof vide for the transmission by said gear train of a second starting, one-to-one, direct drive between said shafts, control means comprising hydraulically operated output shaft speed responsive and engine torque responsive control valvingr to automatically control the engagement and disengagement of said converter lock-up clutch and said planetary direct drive clutch and activation of said planetary gear train for the transmission of said underdrive ratio, and manually operable drive ratio selector means associated with the transmission unit controls and adapted to selectively condition the power transmission unit for the transmission of said first starting direct drive ratio from said converter runner wheel through said input shaft and locked up gear train to said output shaft, and for said second starting underdrive ratio from said converter runner wheel through said input shaft and activated planetary gear train to said output shaft, said output shaft speed and torque responsive control valving being adapted to automatically engage the several clutch means and control activation of the gear train to automatically upshift each of the starting drive ratios to a positively connected, one-toone, direct drive ratio and to automatically disengage said clutches and control activation of said gear train to automatically downshift said, one-to-one, direct drive ratio to the pre-selected starting drive ratio with variations in speed and torque of said output shaft.

9. A power transmission unit for a motor vehicle having an engine, an accelerator therefor, and a manually operable transmission drive ratio selector lever, said power transmission unit comprismg a hydrokinetic torque converter including .an impeller wheel drivingly connected to the engine, a runner wheel, a` guide wheel, and clutch {1l-@21115 adapted t0 be engaged to directly drivmgly connect the impeller and runner wheels, a gear box including an input shaft drivingly connected to the runner Wheel, an output shaft, a planetary gear train adapted to be drivingly connected between said input and output shafts, brake means associated with said gear train adapted to be applied to activate said planetary gear train to provide means for the transmission of a torque multiplying underdrive from said input shaft to said output shaft, and direct drive clutch means associated with said planetary gear train adapted to be engaged to provide means for the transmission of a positive, one-to-one, direct drive from said input shaft to said output shaft, and a control system for said power transmission unit comprising means operable by said drive ratio selector lever to selectively apply the planetary brake means and disengage the converter and. direct drive clutch means to condition said transmission for a rst starting drive through a combination fluid and mechanically generated, torque multiplying, underdrive and to disengage the planetary brake band and converter clutch means and apply the direct drive clutch means to condition said transmission for a second starting drive through a fluid generated, torque multiplying direct drive, said control system including output shaft speed responsive and engine torque responsive control means to automatically operate the planetary brake means each of the clutch means to automatically upshift either of the pre-selected starting, torque multiplying drives to a positively connected, oneto-one, direct drive from the engine to the output shaft.

lil. A power transmission unit for a motor vehicle having an engine, an accelerator therefor, and a manually operable transmission drive ratio selector lever, said power transmission unit comprising a hydrokinetic torque converter including an impeller wheel drivingly connected to the engine, a runner wheel, a guide wheel, and clutch means adapted to be engaged to directly drivingly connect the impeller and runner wheels, a gear boi; including an input shaft drivingly connected to the runner wheel, an output shaft, a planetary gear train adapted to be drivingly connected between said input and output shafts, means associated with said gear train adapted to be applied to activate said planetary gear train to provide means for the transmission oi a torque multiplying underdrive from said inshaft to said output shaft, and direct drive clutch means associated with said planetary gear train adapted to be engaged to provide means the transmission of a positive, one-to-one, direct drive from said input shaft to said output shaft, and a control system for said power transmission unit comprising means operable by said drive ratio selector lever to selectively apply the planetary brake means and disengage the con-- verter and direct drive clutch means to condition said transmission for a first starting drive through a combination uid and mechanically generated, torque multiplying, underdrive and to disengage the planetary brake band and concr clutch means and apply the direct drive clutch means to condition said transmission for second starting drive through a iiuid generated, torque multiplying, direct drive, said control system comprising hydraulically operated output shaft speed responsive and engine torque responsive control valving to automatically operate the planetary brake means and each of the clutch means to automatically upshift either or' the pre-selector starting, torque multiplying, drives to a positively connected, one-to-one, di-

rect drive from the engine to the output shaft, said speed and torque responsive control valving being operative to automatically downshift the positively connected, one,toone, direct drive to the pre-selected starting drive with changes in relationship between the output shaft speed and engine torque.

11. A power transmission unit for a motor vehicle having an engine, an accelerator therefor, and a manually operable transmission drive ratio selector lever, said power transmisison unit compricing a hydrokinetic torque converter including an impeller wheel drivingly connected to the engine, a runner wheel, a guide wheel, and clutch means adapted to be engaged to directly drivingly connect the impeller and runner wheels, a gear box including an input shaft drivingly connected to the runner wheel, an output shaft, a planetary gear train adapted to be drivingly connected between said input and output shafts, brake means associated with said gear train adapted to loe applied to activate said planetay gear train to provide means for the transmission of a torque multiplying underdrive from said input shaft to said output shaft, and direct drive clutch means associated with said planetary gear train adapted to be engaged to provide means for the transmission of a positive, one-toone, direct drive from said input shaft to said output shaft, and a control system for said power transmission unit comprising means operable by said drive ratio selector lever to selectively apply the planetary brake means and disengage the converter and direct drive clutch means to condition the transmission for a first starting drive through a combination fluid and mechanically generated, torque multiplying, underdrive and to disengage the planetary brake band and converter clutch means and apply the direct drive clutch means to condition the transmission for a second starting drive through a fluid generated, torque multiplying, direct drive, said control system comprising fluid operated output shaft speed responsive and engine torque responive control means to automatically operate the planetary brake means and each of the clutch means to automatically upshift either of the preselected starting, torque multiplying, drives to a positively connected, one-to-one, direct drive from the engine to the output shaft, said speed and torque responsive control means being operative to automatically downshift the positively connected direct drive to the selected starting drive with changes in relationship between the output shaft speed and engine torque conditions, and accelerator controlled means to effect a transition from the positively connected, one-to-one, direct drive to the pre-selected starting drive at the will of the vehicle operator and prior to the time said speed and torque responsive control means would automatically elfect such a transition.

l2. A power transmission unit for a motor vehicle having an engine, an accelerator therefor, and a manually operable transmission drive ratio selector lever, said power transmission unit comprising a hydrolrinetic torque converter including an impeller wheel drivingly connected to the engine, a runner wheel, a guide wheel, and clutch means adapted to be engaged to directly drivingly connect the impeller and runner wheels, a gear box including an input shaft drivingly connected to the runner wheel, an output shaft, a planetary gear train adapted to be drivingly connected between said input and output shafts,

brake means associated with said gear train adapted to be applied to activate said planeta-ry gear train'` to provide means for the transmission of av torque multiplying underdrive from said input shaft to said output shaft, and direct drive clutch means associated with said planetary gear train adapted to be engaged to provide means for the transmission of a positive, one-to-one, direct drive from said input shaft to said output shaft, and a pressure iiuid operated control system for said power transmission unit comprising a source of pressure fluid, conduit means connecting said source to said planetary brake means and said converter and direct drive clutch means to provide for pressure fluid operation thereof, a manually operable drive ratio selector valve connected to said conduit means and to said drive ratio selector lever adapted to selectively condition said power transmission unit for a first, starting, combination fluid and mechanically generated, torque multiplying, underdrive and a second, starting, uid generated, torque multiplying, direct drive, control valving connected with said conduit means to control operation of said brake means and said converter and direct drive clutch means including output shaft speed responsive nd engine torque responsive pressure fluid operated control valving adapted to automatically operate said clutches and brake means to upshift each of said pre-selected starting drives to a positively connected, one-to-one, direct drive and to' automatically downshift said positively connected, one-to-one, direct drive to the preselected starting drive with changes in the output shaft speed and the 'engine torque.

13. A power transmission unit for a motor vehicle having an engine, an accelerator therefor, and a manually operable transmission drive ratio selector lever, said power transmission unit comprising a hydrokinetic torque converter including an impeller wheel drivingly connected to th'e engine, a runner wheel, a guide wheel, and clutch means adapted to be engaged to directly drivingly connect the impeller and runner wheels, a gear box including an input shaft drivingly connected to the runner wheel, an output shaft, a planetary gear train adapted to be 'drivingly connected between said input and output shafts, brake means associated with said gear train adapted to be applied to activate said planetary gear train to provide means for the transmission ofl a torque multiplying underdrive from said input shaft to said 'output shaft, and direct drive clutch means associated with said planetar gear train adapted to be lengaged to provide means for the transmission of a positive, one-to-one, direct drive from said input shaft to said output shaft, and a pressure fluid operated control system for said power transmission unit comprising a source of pressure uid, conduit means connecting said source to said planetary brake means and said converter and direct drive clutch means to provide for pressure Vfluid operation thereof, a manually operable drive ratio selector valve connected to said conduit means and to said drive ratio selector lever adapted to selectively condition said power transmission unit for a starting, combination fluid and mechanically generated, torque multiplying, underdrive and a second, starting, fluid generated, torque multiplying, direct drive, control valving vconnected with said conduit means to control operation of said brake means and said converter and direct drive clutch means including output shaft speed responsive and engine torque responsive pressure fluid operated control valving adapted to automatically operate said clutches and brake means to upshift each of said pre-selected starting drives to a positively connected, one-to-one, direct drive and to downshift said positively connected, one-to-one, direct drive to the pre-selected starting drive with changes in the output shaft speed and engine torque, said control system including an accelerator controlled kickdown valve adapted to effect a downshift of the positive, one-to-one, direct drive to the pre-selected starting drive at the will of the vehicle operator.

14. A power transmission unit for a motor vehicle having an engine, an accelerator therefor, and a manually operable transmission drive ratio selector lever, said power transmission unit comprising a hydrokinetic torque converter including an impeller wheel drivingly connected to the engine, a runner wheel, a guide wheel, and clutch means adapted to be engaged to directly drivingly connect the irnpelle` and runner wheels, a gear box including an input shaft drivingly connected to the runner wheel, an output shaft, a planetary gear train adapted to be drivingly connected between said input and output shafts, brake means associated with said gear train adapted to be applied to activate said planetary gear train to provide means for the transmission of a torque multiplying underdrive from said input shaft to said output shaft, and direct drive clutch means associated with said planetary gear train adapted to be engaged to provide means for the transmission of a positive, one-to-one, direct drive from said input shaft to said output shaft, and a pressure fluid operated control system for said power transmission unit comprising a source of pressure fluid, conduit means connecting said source to said planetary brake means and said converter and direct drive clutch means to provide for pressure fluid operation thereof, a manually operable drive ratio selector valve connected to Said conduit means and to said drive ratio selector lever adapted to selectively condition said power transmission unit for a rst, starting, combination fluid and mechanically generated, torque multiplying, underdrive and a second, starting, fluid generated, torque multiplying, direct drive, control valving associated with said conduit means to control operation of said brake means and said converter and direct drive clutch means including output shaft speed responsive and engine torque responsive pressure fluid operated control valving adapted to automatically operate said control valving to upshift each of said pre-selected starting drives to a positively connected, one-to-one, direct drive and to downshift said positively connected, one-to-one, direct drive to the preselected starting drive with changes in the output shaft speed and the engine torque, said manually operable drive ratio selector valve including means to overrule the automatic operation of the speed and torque responsive control valving whereby said power transmission unit may be locked in a positively connected underdrive ratio transmitted through said planetary gear unit.

15. A power transmission unit for a motor vehicle having an engine, an accelerator therefor, and a manually operable transmission drive ratio selector lever, said power transmission unit comprising a hydrolrinetic torque converter including an impeller wheel drivingly connected to the engine, a runner wheel, a guide wheel, and clutch means adapted to be engaged to directly drivingly connect the impeller and runner wheels, a gear box including an input shaft drivingly connected to the runner wheel, an output shaft, a planetary gear train adapted to be drivingly connected between said input and output shafts, brake means associated with said gear train adapted to be applied to activate said planetary gear train to provide means for the transmission of a torque multiplying underdrive from said input shaft to said output shaft, and direct drive clutch means associated with said planetary gear train adapted to be engaged to provide means for the transmission of a positive, one-to-one, direct drive from said input shaft to said output shaft, and a pressure fluid operated control system for said power transmission unit comprising a source of pressure fluid, conduit means connecting said source to said planetary brake means and said converter and direct drive clutch means to provide for pressure fluid operation thereof, a manually operable drive ratio selector valve connected to said conduit means and to said drive ratio selector lever adapted to selectively condition said power transmission unit for a first, starting, combination uid and mechanically generated, torque multiplying, underdrive and a second, starting, fiuid generated, torque multiplying, direct drive, control valving associated with said conduit means to control operation of said brake means and said converter and direct drive clutch means including output shaft speed responsive and engine torque responsive pressure fluid operated control means adapted to automatically operate said control valving to upshift each of said pre-selected starting drives to a positively connected, one-to-one, direct drive and to downshift said positively connected, one-to-one, direct drive to the pre-selected starting drive with changes in the output shaft speed and the engine torque, said manually operable drive ratio selector valve including means to overrule the automatic operation of the speed and torque responsive control valving whereby said power transmission unit may be locked in a positively connected underdrive ratio, and accelerator actuated, valve means connected with said control valving adapted to overrule the automatic operation of said output shaft speed responsive and engine torque responsive control valving to effect a downshift from the positively connected, oneto-one, direct drive to the pre-selected starting drive at the will of the vehicle operator.

16. A power transmission unit for a motor vehicle having an engine, an accelerator therefor, and a manually operable transmission drive ratio selector lever, said power transmission unit comprising a hydrokinetic torque converter including an impeller wheel drivingly connected to the engine, a runner wheel, a guide wheel, and clutch means adapted to be engaged to directly drivingly connect the impeller and runner wheels, a gear box including an input shaft drivingly connected to the runner wheel, an output shaft, a planetary gear train adapted to be drivingly connected between said input and output shafts, brake means associated with said gear train adapted to be applied to activate said planetary gear train to provide means for the transmission of a torque multiplying underdrive from said input shaft to said output shaft, and direct drive clutch means associated with said planetary gear train adapted to be engaged to provide means for the transmission of a direct drive from said input shaft to said output shaft, and a pressure fluid operated control system for said powerv transmission unit comprising valve means operable by said drive ratio selector lever to selectively apply the planetary brake means and disengage the converter and direct drive clutch means to condition said transmission for a first starting drive through a combination fluid and mechanically generated, torque multiplying, underdrive, vand to disengage the planetary brake band and converter clutch means and apply the direct drive clutch means to lock up said planetary gear train and condition said transmission for a second starting drive through a fluid generated, torque multiplying direct drive, and output shaft speed responsive and engine torque responsive pressure fiuid operated control valving cooperatively arranged to automatically operate the planetary brake means and each of the clutch means to automatically convert either of the pre-selected starting, torque multiplying drives to a positively connected, one-to-one, direct drive from the engine to the output shaft, said speed and torque responsive valving being under the control of an accelerator operated control valve and being arranged such that on initiating drive through the first starting drive ratio the speed and torque responsive valving will rst effect engagement of said converter clutch means and subsequently cause substantially simultaneous release of the planetary brake means and engagement of the direct drive clutch, said speed and torque responsive valving also being arranged such that on initiating drive through the second starting drive ratio the converter clutch means will be subsequently engaged when the speed and torque of the output shaft have attained predetermined relationships.

17. A power transmission unit as set forth in claim 16 wherein the pressure uid operated control system includes a compensator valve unit connected to the speed responsive pressure uid operated control valving to selectively apply different clutch engaging operating pressures to the direct drive clutch depending on which of the starting ratios has been pre-selected.

18. A power transmission unit as set forth in claim 16 wherein the pressure fiuid operated control system includes valve means operable by a predetermined movement of said accelerator to provide means to overrule the automatic operation of said output shaft speed and torque responsive pressure fluid operated valving whereby the positively connected direct drive can be kicked down to the pre-selected starting drive ratio.

19. A power transmission unit for a motor vehicle having an engine, an accelerator therefor, and a manually operable transmission drive ratio selector lever, said power transmission unit comprising a hydrokinetic torque converter including an impeller wheel drivingly connected to the engine, a runner wheel, a guide wheel, and converter clutch means adapted to be engaged to directly drivingly connect the impeller and runner wheels, a gear box including an input shaft drivingly connected to the runner Wheel, an output shaft, a planetary gear train adapted to be vdrivingly connected between said input output shafts, brake means associated with gear train adapted to be applied to activate said planetary gear train to provide means for the transmission of a torque multiplying underdrive from said input shaft to said output shaft, ant direct drive clutch means associated with said planetary gear train adapted to be engaged to providev means for thetransmission of a direct,

31 one-to-one, drive from said input shaft to said output shaft, and a pressure fluid operated control system for said power transmission unit comprising a source of pressure fluid, conduit means connecting said source to said planetary brake means and to said converter clutch means and direct drive clutch means to provide for pressure fluid operation thereof, a manually operable drive ratio selector valve connected to said conduit means and to said drive ratio selector lever adapted to be operated to selectively condition said power transmission unit for a rst, starting combination fluid and mechanically generated, torque multiplying, underdrive and a second, starting, uid generated, torque multiplying, direct drive, control valving connected with said conduit means to control operation of said braise means and said converter clutch means and direct drive clutch means, and output shaft speed responsive and engine torque responsive pressure fluid operated control valving adapted to automatically operate said several clutch and brake means to convert each of said pre-selected starting drives to a positively connected, one-to-one, direct drive and to automatically convert said positively connected, one-to-one, direct drive the pre-selected starting drive with changes in the speed and torque relationship of said output shaft, said speed and torque responsive control valving being under the control of an accelerator operated control valve that is connected to the said conduit means, said speed and torque responsive valving being arranged such that on initiating drive through the pre-selected first starting drive the converter clutch will be engaged prior to release of the brake means and engagement of the direct drive clutch to effect the automatic upshift to direct drive and when initiating drive through the pre-selected second starting drive the speed and torque responsive vali/ing retains said direct drive clutch engaged prior to and after engagement of the converter clutch.

20. A power transmission unit for a motor vehicle having an engine, an accelerator therefor, and a manually operable transmission drive ratio selector lever, said power transmission unit comprising a hydroknetic torque converter including an impeller wheel drivingly connected te the engine, a runner wheel, a guide wheel, and clutch means adapted to be engaged to directly drivingly connect the impeller and runner wheels. a gear box including an input shaft drivinglv connected to the runner wheel, an output shaft, a planetary gear train adapted to be drivingly connected between said input and output shaft. brake means associaited with said gear train adapted to be applied to activate said planetary gear train to provide means for the transmission of a torque multiplying underdrive from said input shaft to said output shaft, and direct drive clutch means associatedwith said planetary gear train adapted to be engaged to provide means for the transmission of a one-to-one, direct drive from said input shaft to said output shaft, and a pressure fluid operated control system lfor sai-- power transmission unit comprising a source of pressure fluid, conduit means connecting said source to said planetary brake means and said converter and direct drive clutch means to provide for pressure uid operation thereof, a manually operable drive ratio selector valve connected to said conduit means and to said drive ratio selector lever adapted to be operated to selectively condition said power transmission unit for a first, starting, combination fluid and mechanically generated, torque multiplying, underdrive and a second, starting, uid generated, torque multiplying, direct drive, control valving connected with said conduit means to control operation of said brake means and said converter and direct drive clutch means, including output shaft speed responsive and engine torque responsive pressure fluid operated control valving adapted to automatically operate said several clutch and brake means to convert each of said starting drives to a positively connected, one-to-one, direct drive and to automatically convert said positively connected direct drive to the preselected starting drive with changes in the Speed and torque relationship of said output shaft, said control system including an accelerator operated valve to control operation of said speed and torque responsive valving.

2l. In a power transmission unit as set forth in claim 20 wherein the pressure fluid operated control system includes a compensator valve to modify the pressure fluid applied to the direct drive clutch to effect engagement thereof depending on which of the starting drives is preselected, said compensator valve applying a greater clutch engaging pressure to the direct drive clutch when the second starting direct drive is utilized for initiating drive than when the first starting drive is utilized for drive initiation.

22. In a power transmission unit as set forth in claim 20 wherein the pressure fluid operated control system includes an accelerator operated valve to overrule automatic operation of the torque and speed responsive valving and provide means for effecting a downshift from the positive direct drive to the pre-selected starting drive at the will of the operator.

23. In a power transmission unit as set forth in claim 20 wherein the pressure fluid operated control system includes a compensator valve unit adapted to Vary the points of output shaft speed at which the converter clutch means will be engaged depending on whether the transmission is set for initiation of drive in said first or s'md second starting drive.

24. In a power transmission unit as set forth in claim 23 wherein said compensator valve unit is arranged to effect engagement of said converter clutch means at a lower output shaft speed when said transmission is set for initiation ci drive in the first starting drive than when the said transmission is set for the initiation of drive in the second starting drive.

PAUL C. ACKERMAN.

References Cited in the ille of this patent UNITED STATES PATENTS Numhe Name Date 2,332,593 Nutt et al. Oct. 26, 1943 2,374,303 Osborne Apr. 24, 1945 2,478,868 Hasbany Aug. 9, 1949 2,516,208 Hasbany July 25, 1950 2,562,464 Jandasek July 31, i 2,568,007 Jandasek Sept. 18, 1951 2,640,373 Jandasek June 2, 1953 OTHER REFERENCES Packard Servicemans Training Book, June 27, 1949, Packard Motor Car Co.

Product Engineering, vol. 21, No. 1 (pages 94 .to 97, inc1.). 

